Root canal file

ABSTRACT

AN ENDODONTIC INSTRUMENT FOR TREATING A PULP CANAL, INCLUDING AN ELONGATED MEMBER HAVING A FLUTED CUTTING PORTION AT ONE END, A HANDLE AT THE OTHER AND AN INTERMEDIATE PART BETWEEN THE CUTTING PORTION AND THE HANDLE, A STOP MEMBER BEING POSITIONABLE ON THE INTERMEDIATE PORTION AT DIFFERENT LONGITUDINAL LOCATIONS AS ESTABLISHED BY LATERALLY PROJECTING RIBS TO ADJUST THE EFFECTVE LENGTH OF THE CUTTING PORTION, THE STOP MEMBER HAVING TWO ABUTMENT SURFACES, EACH OF WHICH MAY BE POSITIONED ADJACENT THE TIP OF THE CUTTING PORTION FOR VARYING THE SETTING OF THE STOP MEMBER. ALTERNATIVELY, THE INTERMEDIATE PORTION OF THE ELONGATED MEMBER MAY BE THREADED AND THE STOP MEMBER IN THE FORM OF A NUT.

Feb. 16, 1971 W, FFR 3,562,913

ROOT CANAL FILE Filed Aug. 11, 1969 INl liNTOR.

2 2 DENNIS w. SAFFRO I5 BY .r fl

' m J '2. 1 no.9 7 at ATTOR N EYS United States Patent 3,562,913 ROOT CANAL FILE Dennis W. Saffro, 10536 Garwood Place, West Los Angeles, Calif. 90024 Filed Aug. 11, 1969, Ser. No. 848,835 Int. Cl. A61c /02 US. Cl. 32-57 8 Claims ABSTRACT OF THE DISCLOSURE An endodontic instrument for treating a pulp canal, including an elongated member having a fluted cutting portion at one end, a handle at the other and an intermediate part between the cutting portion and the handle, a stop member being positionable on the intermediate portion at different longitudinal locations as established by laterally projecting ribs to adjust the effective length of the cutting portion, the stop member having two abutment surfaces, each of which may be positioned adjacent the tip of the cutting portion for varying the setting of the stop member. Alternatively, the intermediate portion of the elongated member may be threaded and the stop member in the form of a nut.

BACKGROUND OF THE INVENTION Field of the invention This invention pertains to an endodontic instrument for treating pulp canals.

The prior art In filing or reaming the root canals of endodontically involved teeth, it is important to limit the depth of penetration of the file or reamer to avoid injury. In the past, a small piece of rubber dam or elastic has been used for this purpose. However, this has not been satisfactory in that it does not allow accurate determination of the depth of the canal, nor does it provide a positive limitation of the penetration. Also, it is time consuming in its use.

There has been provided, in addition, an adjustable device for files and reamers in which the end of the instrument is provided with a transverse bend received in a slot in a handle assembly. Through rotation of a nut, the transversely bent portion is caused to shift axially relative to the handle device, thereby varying the length of the fluted portion of the instrument projecting beyond the handle. While offering some advantages, this arrangement is complex, expensive and somewhat difficult to use.

SUMMARY OF THE INVENTION The present invention provides an improved, simplified pulp canal instrument which provides for a precisely determined length of the cutting portion of the instrument. The file or reamer includes a fluted end portion of conventional construction, above which is a shank having laterally projecting ribs at predetermined spacings. The opposite end of the device is provided with an appropriately curved handle for facilitating its manipulation by the dentist. A disc having a slot is positionable along the shank between any set of adjacent ribs, and presents an abutment surface adjacent the fluted end to limit the penetration into the root canal. By selection of the ribs between which the disc is positioned, it may be set at predetermined distances from the tip of the fluted end. Once the depth of the root canal has been established, the successively used files or reamers of different sizes may be given the same setting to assure continued safe operation.

Preferably, an abutment surface is provided on either end of the clip, the surfaces being spaced differently from the portion of the device that engages the ribs, so that "ice when one abutment surfaces faces the tip the distance is different from that achieved when the other abutment surface is positioned adjacent the tip. This allows additional close settings through appropriate selection of the surface facing the tip. In an alternate arrangement, the shank may be threaded, with a nut received thereon for rotation to provide axial adjustment.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevational view, partially in section, illustrating the endodontic instrument of this invention as used in treating a pulp canal;

FIG. 2 is an enlarged fragmentary elevational view of the shank portion of the instrument;

FIG. 3 is a top plan view of the clip which is associated with the shank to provide a stop limiting the penetration of the instrument;

FIG. 4 is a bottom plan view of the clip;

FIG. 5 is an enlarged sectional view taken along line 55 of FIG. 3;

FIG. 6 is an enlarged sectional view taken along line 6-6 of FIG. 3;

FIG. 7 is a fragmentary elevational view showing the stop member positioned on the shank with one abutment surface facing the tip of the instrument;

FIG. 8 is a view similar to FIG. 7, but with the stop member positioned so that the other abutment surface faces the tip of the instrument;

FIG. 9 is a sectional view, partially in elevation, showing how the stop member receives the shank portion and is positioned longitudinally;

FIG. 10 is a fragmentary elevational view of a modification of the invention using a threaded member as the stop; and

FIG. 11 is a view similar to FIG. 10 showing the addition of a jam nut to assist in retaining the setting of the stop member.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The device of this invention is made up of a two-part assembly, one portion including a file or reamer and the other serving as a stop to limit the penetration of the instrument. The former unit 10, which may be of stainless steel, has a tapered, fluted end part 11, which performs the filing or reaming as the device is used during the treatment of endodontically involved teeth. The end portion 11 preferably is made to correspond to the standard sizes specified by the American Dental Association. In other words, the files and reamers will be made to have their fluted end portions of different diameters in accordance with existing specifications. Typically, the fluted portion 11 is 16 millimeters in length.

Above the fluted portion 11 is a calibrated section 12 having spaced, accurately positioned ribs 13 projecting laterally outwardly at right angles to the longitudinal axis of the unit 10. Corresponding locations on the ribs 13 are spaced apart equally in a direction axially of the device 10. Thus, the lower surfaces 14 of the ribs 13, as the device is shown in FIG. 2, have equal spacing between them, typically being one millimeter apart. Intermediate the ribs 13 are markings 15 which indicate the distance in millimeters between the adjacent lower rib surface 14 and the tip 16 of the fluted portion 11.

Above the calibrated section 12 is a handle 17 which may have a knurled exterior and be convergent at its midportion. This allows it to be gripped easily by the dentist and to be comfortable to the hand. The handle 17 suitably is around nine millimeters long.

The other portion of the device is a clip 18 of alumi num or other material which will not rust or become distorted upon the heat of sterilization. The clip 18 is in the form of a circular disc provided with a slot 19 extending inwardly from the side edge of the disc. The slot 19 includes a narrower outer portion 20 and an enlarged central portion 21. In the axial direction, the slot 19 has an intermediate wall 22 of reduced lateral dimension. This provides wall sections 23 and 24 at the ends of the clip 18 where the slot is of wider lateral dimension. The depth of the wall section 23 is the same as the thickness of any of the ribs 13. The wall section 24 is longer, being equal to the width of a rib 13 plus one-half the distance between corresponding positions on adjacent ribs. In the example shown, where the undersurfaces of adjacent ribs are one millimeter apart, the Wall portion 24 is as long as the thickness of a rib 13 plus one-half millimeter.

The outer circumferential wall 25 of the clip 18 includes a laterally narrower portion 26 at the same end as the longer end wall 24. This provides a ready identification from the outside of the clip 18 to tell the two ends of the clip apart.

The end walls 27 and 28 of the clip 18 are flat and radial. Similarly, the shoulder 29 between the walls 22 and 23 is radial and parallel to the end walls 27 and 28. The other shoulder 30 between the interior walls 22 and 24 likewise is radial.

In use of the device of this invention, the clip 18 is assembled onto the calibrated portion 12 of the file or reamer 10 at an appropriate location to cause the overall working length of the file to be a predetermined dimension. In attaching the clip 18 to the calibrated section 12, the entrance part 20 of the slot 19 becomes pried outwardly as the resilient clip 18 is pushed onto the section 12 in one of the recesses provided between a pair of ribs 13. The clip 18 snaps in place as the section 12 moves into the inner portion 21 of the slot. The wall portion 22 is dimensioned so that it then extends between the two adjacent ribs 13, being substantially coterminous with this space so that the ribs act as abutments that engage the shoulders 29 and 30 to hold the clip 18 against movement longitudinally of the unit 10.

When positioned with the radial surface 27 facing toward the fluted portion 11, as illustrated in FIG. 7, the radial surface 27 then becomes flush with the bottom edge 14 of the lower rib 13 of the numbered space where the clip is positioned. This means that the overall working length of the file 10 is the same as that of the number of the space occupied by the clip. In the example shown in FIG. 7, with the clip 18 covering the number 23, there are 23 millimeters from the radially projecting surface 27 to the tip 16 of the fluted portion 11 of the file or reamer. Thus, the clip 18 is readily snapped into place on any of the numbered spaces in the calibrated portion 12 of the file to quickly provide the file with a working length corresponding precisely to the number selected on the file.

Reversing the position of the clip 18, as shown in FIG. 8, provides for a one-half millimeter adjustment of the length of the file 10. If the clip 17 is turned over so that the radial surface 28 faces the tip 16 of the fluted portion 11 of the file 10 the length of the file is reduced by onehalf millimeter. This is because the depth of the portion at the well 24 of the slot 19 is that of the thickness of a rib 13 plus one-half millimeter. Therefore, when the clip 18 is on the portion with the number 23, as shown in FIG. 8, and the surface 28 faces the tip 16 of the fluted portion 11, the effective length of the file is 22.5 millimeters. The ability to set the clip 18 at one-half millimeter increments allows the working length of the file to be given very fine adjustments.

The file or reamer is used, as shown in FIG. 1, by employing the radial surface 27 or 28 as a constant and accurately located abutment to limit the penetration of the fiuted end 11 into the root canal '32. After first ascertaining the appropriate length for the file or reamer, the clip 18 is positioned in the desired location on the calibrated portion 12, so that it then forms a shoulder that can be brought into engagement with the surface at the 4 outer end of the canal 32 when the fluted end 11 is inserted into the canal. As a result, the fluted portion 11 can enter the canal 32 to the desired depth but no further.

In the embodiment of FIG. 10, the clip 18 is replaced with a nut 34, while the file is provided with a threaded section 35 in place of the ribs 13. The nut 34 serves the same purpose as the clip 18, being adjusted axially of the file by rotation relative to the threaded section 35. Preferably, there is a slight interference fit between the threads of the nut and those of the file so that the nut will retain its setting after it has been appropriately positioned. The length of the file is established by use of a measuring scale (not shown) to set the distance between the bottom radial surface 36 of the nut 34 and the end of the fluted section 11.

In the embodiment of FIG. 11, a second nut 37 is used to act as a jam nut in retaining the setting of the nut 34 that establishes the length of the file.

The versions with the nut as the stop element have the advantage of providing an infinite variation of the setting of the overall length of the file or reamer. However, they lack the convenience of the readily identifiable length setting as accomplished through the use of the clip and the numbers 15, requiring a separate scale for such adjustment. Moreover, the one-half millimeter settings possible through the use of the clip 18 are sufficiently fine for nearly all purposes. The clip 18 also assures that no variation in length can occur once the adjustment has been made, as inadvertent rotation will not vary the file length.

I claim:

1. A root canal file comprising an elongated member,

one end portion of said elongated member having cutting means thereon,

a handle portion at the opposite end of said elongated member,

and an intermediate portion between said cutting means and said handle portion,

and a stop means movable longitudinally of said intermediate portion,

said stop means including an element having an abutment surface adjacent said cutting means,

said element having a slot therein,

said intermediate portion being receivable in said slot,

said intermediate portion having a plurality of spaced abutment means selectively engageable with said element when said intermediate portion is received in said slot for positioning said element at different locations longitudinally of said intermediate portion for thereby locating said abutment surface at different distances from the tip of said one end portion.

2. A device as recited in claim 1 in which said element includes a duality of abutment surfaces,

one of said abutment surfaces being on one side of said element, and the other of said abutment surfaces being on the other side of said element,

said element being positionable to locate either of said abutment surfaces adjacent the tip of said one end portion, said abutment surfaces of said element being spaced different distances from said tip of said one end portion when located adjacent thereto for thereby providing an adjustment of the effective distance from said tip to said element.

3. A device as recited in claim 1 including in addition indicia on said intermediate portion for indicating the distance between said element and said tip of said one end portion at said different locations longitudinally of said intermediate portion.

4. A device as recited in claim 1 in which for said abutment means said intermediate portion includes spaced ribs projecting outwardly therefrom at predetermined locations longitudinally of said intermediate portion, said element having surfaces receivable between adjacent ones of said ribs and engageable therewith for thereby positioning said element longitudinally of said intermediate portion.

5. A device as recited in claim 4 in which said element has two of said abutment surfaces,

one of said abutment surfaces being on one side of said element, the other of said abutment surfaces being on the opposite side of said element,

said element being selectively positionable with either of said aubtment surfaces thereof adjacent said tip of said one end portion, said abutment surfaces being spaced different distances from said surfaces of said element receivable between said adjacent ribs,

whereby the etfective distance from said tip of said one end portion to said element is adjustable by selectively positioning said abutment surfaces of said element adjacent said tip. 6. A device as recited in claim 4 in which said slot has a relatively wide inner portion and a relatively narrow outer entrance portion, said element being of resilient material,

said entrance portion of said slot being narrower than the lateral dimension of said intermediate portion between said ribs, said inner portion of said slot being dimensioned to receive said intermediate portion between said ribs,

whereby said element is retained on said intermediate portion. 7. A root canal file comprising an elongated member,

one end portion of said elongated member having cutting means thereon, a handle portion at the opposite end of said elongated member, and an intermediate portion between said cutting means and said handle portion,

said intermediate portion having external threads thereon, and stop means movable longitudinally of said intermediate portion,

said stop means having an abutment surface adjacent said cutting means, said stop means including an internally threaded member received on and rotatable relative to said intermediate portion,

whereby said stop means is positionable selectively on said intermediate portion for locating said abutment surface at different distances from the tip of said one end portion. 8. A device as recited in claim 7 including in addition a jam nut for engaging said internally threaded member and maintaining the setting thereof.

References Cited UNITED STATES PATENTS 3,330,040 7/1967 Kahn 32--57 3,358,826 12/1967 Siegel 3240 ROBERT PESHOCK, Primary Examiner 

